The present invention relates generally to electromagnetic interference and electromagnetic pulse seals, and more specifically to a novel electromagnetic pulse rotary seal.
Electrical circuitry often must be protected from disruptions caused by electromagnetic interference (EMI) entering the system. External EMI energy is an undesired conducted or radiated electrical disturbance that can interfere with the operation of electronic equipment. With the development of nuclear explosives another type of electromagnetic radiation has been observed. A nuclear explosion, and in some circumstances large scale chemical explosions, produces a sharp pulse (large impulse-type) of radio frequency (long wave length) electromagnetic radiation. The intense electric and magnetic fields created by electromagnetic pulse (EMP) energy can damage unprotected electrical and electronic equipment over a wide area. As a result, a demand has appeared for seals having substantial shielding effectiveness against EMI and EMP energy threats.
Prior art development of EMI and EMP seals has primarily concentrated on two types of seals: electrical connectors, as illustrated in U.S. Pat. No. 4,330,166 to Cooper et al; and, static housing or gasket seals for equipment cabinets, as illustrated in U.S. Pat. No. 4,061,413 to Keller. The prior art does not disclose dynamic seals to provide shielding against EMI and EMP energy at the intersection of part surfaces moving in relation to one another as, for example, at the line where a rotating shaft extends through a housing.
It is, therefore, a principal object of the present invention to provide a dynamic seal that will effectively shield against EMI and, particularly, EMP radiation.
It is another object of the present invention to provide a rotary seal for a rotating shaft extending from an opening in a housing.
A feature of the present invention is that it automatically compensates for manufacturing tolerances in its construction, axial misalignment, or any other unpredictable part movement tending to interrupt the seal.
An advantage of the present invention is that it is easily inserted and removed.
Another advantage of the present invention that it may be easily retrofitted to existing equipment.